W8NF:
> I always thought my IC-735 was a nice (but not
> great) radio until I started trying to listen to
> DX on 80 and 160. It was nearly useless.
> Switched to using a Drake R-4B and suddenly I
> could hear. The problem was PLL phase noise in
> the Icom. Not fixable with external anythings.
I have an IC-738, very similar audio chain to the IC-735. When I got it to
replace an old Ten-Tec 580 I found that the 160mtr rx was much worse on
the new rig. I discovered that the rx quality (ability to copy weak cw & ssb)
was dramatically better if I ran the audio from the product detector output to
an external high quality audio amp. I suspect the stock audio circuitry has
poor IMD. The external audio also allowed external digital filters to work.
Putting them on the IC-738 output resulted in no improvement, while putting
them on the external audio amp output did result in improvement in some
conditions.
Rod VE7VV
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